Transcript exp01
Electronic Instrumentation Experiment 1 * Part A: Circuit Basics, Equipment, Sound Waves * Part B: Resistors, Circuit Analysis, Voltage Dividers * Part C: Capture/PSpice Course Web Resources and Logistics http://hibp.ecse.rpi.edu/%7Econnor/education/Ele cInst.html Open Shop and Office Hours Announcements (printers) Calendar Links by Experiment (http://hibp.ecse.rpi.edu/~connor/education/EILink s.html ) Homework Assignments (LMS) Quiz Information Motivation Modern Systems • mechanical component • electrical component • (computer component) You will be able to communicate with EE’s You will be able to take the electronics sections of the FE exam You will be using Engineering problem solving skills. Automobile Electronics Previously all mechanical systems have become increasingly electronic Over the past few years, for example, the automobile has begun to use more computers (microcontrollers) How many microcontrollers are typically found in a modern automobile? Automobile Electronics Part A Circuit Basics Equipment Sound Waves Physical Model for a DC circuit pump = voltage source water = flow of current ocean = ground pipe = wire Physical Model for Resistance pebbles in pipe = resistance to flow of current Symbols Physics vs. Electronics Ohm’s Law : V = IR High pressure P1 I Constriction Pump I P2 Low pressure Alternating Current Generators http://micro.magnet.fsu.edu/electromag/java/generator/ac.html http://www.walter-fendt.de/ph11e/generator_e.htm AC Circuits v(t ) i (t ) R Note symbol for AC voltage source Review of Sinusoids Vrms explanation http://www.practicalphysics.org/go/Guidance_107.html More on Phase Shift Negative phase shift: “Lag in phase, lead in time” 1.0V 0V -1.0V 0s 0.4ms 0.8ms 1.2ms 1.6ms 2.0ms V(V1:+) t0 0.08ms 2 (1K ) (0.08m)( 2K )( ) 0.5 rad Time Positive phase shift: “Lead in phase, lag in time” 1.0V 0V -1.0V 0s 0.4ms 0.8ms 1.2ms 1.6ms 2.0ms V(V1:+) t0 0.08ms 2 (1K ) (0.08m)( 2K )( ) 0.5 rad Time Special Cases of Phase Shift t0 t0 2ft0 2 T 0 rad 1.0V rad 1.0V 0V 0V -1.0V -1.0V 0s 0.5ms 1.0ms 0s V(V1:+) 0.5ms V(V1:+) Time Time 2 rad 1.0V 0V -1.0V -1.0V 0.5ms V(V1:+) 2 rad 1.0V 0V 0s 1.0ms 1.0ms 0s 0.5ms V(V1:+) Time Time 1.0ms Sinusoid Units DC Source E3631A – Only for section 2 ADJUST VOLTAGE LEVEL TOGGLE OUTPUT ON/OFF -25 to 0 VOLTS 0 to 6 VOLTS GROUND GROUND 0 to 25 VOLTS Do Not Use Note: The connection that looks like the ground symbol is the ground for the building, not the return path for the circuit. DC Source for JEC-4201 Function Generator 33120A – Only available in JEC 4107 Note: The SYNC connection will give you a signal, but it will not be the one you have set the function generator to display. Do not accidentally plug into it. Function Generator Figure A-1 (referred to in experiment) We have a new board example: Func Gen 1 = AWG1 Digital Multimeter 34401A – We will have some hand held meters in section 1 for resistance measurements Note: Always use the voltage plugs on the right as indicated. Digital Multimeter Figure A-1 (referred to in experiment) We have a new board example: ADC+ and GND =A1+ and GND The IOBoard can read voltages but it isn’t an Ohmmeter, We will use hand held meters for resistance measurements Oscilloscope 54600B – you guessed it – JEC 4107 Note: Black lead of scope channel is ALWAYS ground Protoboards Note: Banana connectors are not connected internally to the holes in the board. Check continuity of power rails at top and bottom. Reading Resistors Bands: XYZT Resistance = XY 10 Z T % http://www.dannyg.com/javascript/res/resload.htm How Ears Work Pitch = frequency Amplitude = loudness Some pitches sound louder to your ears. http://members.aol.com/tonyjeffs/text/dia.htm In Class Problem Across the top please put: Name: Section ((MR) or (TF)): Date Question 1: From diagram A: Which of the following statements is true given the direction of the current flow. a.) P2 < P1 b.) P2 = P1 c.) P2 > P1 Question 2: Draw the circuit equivalent of diagram A, label current flow and voltage (+ and – on the voltage source). Question 3: Draw an AC signal with the following parameters Vp-p=6V Vave=0V Frequency=2KHz Label the axis, label the amplitude and period P1 I Pump I Constriction P2 Diagram A Part B Resistors Voltage Dividers Impedance Capacitors and Inductors Equipment Impedances Circuit Analysis Agilent Intuilink Software Combining Resistors in Series Combining Resistors in Parallel Measuring Voltage Total Voltage: V 1 VR1 VR 2 Voltage across resistors: VR1 VA VB VR 2 VB VC Voltage at points wrt GND: VA V 1 VB VR 2 VC 0 Voltage Dividers The voltage is divided up in a manner that is proportional to the resistances of the resistors in a series circuit. More on Voltage Dividers 4V 4V 3K 1K 5V 1K 3K 1K 8K 5V 1K 8K You cannot use a voltage divider on a non-series circuit. Always add up resistors relative to ground to get the voltage at a point. 2V 4 K 4V 4K 4K You can use a voltage divider on a series portion of a circuit. Impedance vs. Resistance Resistance is a property of a material that causes a reduction in the rate of flow of electrons. Impedance is the reduction in the rate of flow of electrons caused by the material (resistance) AND other the properties of the component involved (reactance). Resistors have no reactance. So the impedance of a resistor is equal to its resistance only. Reactance varies with the frequency of the input. Resistance remains the same at all frequencies. Both impedance and resistance are measured in ohms. Impedance Definition: A general measure of how a component or group of components pushes against the current flowing through it. Impedance = resistance + reactance Impedance is used to refer to the behavior of circuits with resistors, capacitors and other components. When we consider components in a theoretical circuit diagram, the impedance of inductors and capacitors is their reactance only. Any resistance is modeled separately as a resistor. So theoretical capacitors and inductors have impedance, but no resistance. Comparison of Components V IR RT R1 R2 RT1 R11 R21 R R Capacitors Capacitors consist of two plates with a dielectric material in-between. When a potential difference is placed across the plates, a charge builds up until it is large enough to cause a discharge across the plates through the material. Reading Capacitors - towards ground Larger capacitors have the number of microfarads written on them directly. Smaller capacitors use a code based on the number of picofarads. We generally use microfarads, so… XYZ = XY * 10Z * 10-6 mF Capacitors in Series Capacitors in Parallel Understanding Capacitor Behavior Capacitor Impedance Note: Real capacitors have effectively no resistance, so impedance is reactance for all capacitors. Comparison of Components C VR I R R IC C dVC dt RT R1 R2 CT1 C11 C21 RT1 R11 R21 CT C1 C2 R open circuit R short circuit Inductors An inductor is a coil of wire through which a current is passed. The current can be either AC or DC. Inductors dI L VL L dt This generates a magnetic field, which induces a voltage proportional to the rate of change of the current. Combining Inductors Inductances add like resistances Series Parallel L L1 L2 ... LN 1 1 1 1 ... L L1 L2 LN Inductor Impedance Note: Real inductors always have a small resistance (that is not shown in these circuits). The impedance of the theoretical inductor shown is only its reactance. Comparison of Components C VR I R R IC C dVC dt L VL L dI L dt RT R1 R2 CT1 C11 C21 LT L1 L2 RT1 R11 R21 CT C1 C2 LT1 L11 L21 R open circuit R short circuit open circuit short circuit Equipment Impedances Each measuring device changes the circuit when you use it. The impedance of the device helps you understand how much. Device Impedances • • • • • Function Generator: 50 ohms ‘Scope: 1Meg ohms DMM (DC voltage): 10Meg ohms DMM (AC voltage): 1Meg ohms DMM (DC current): 5 ohms (negligible) Effect of Impedance on Circuit Function generator thinks it is putting out the same thing. Output is clearly different. Effect of Impedance on Circuit Vout Vout Vout Vout 50 Vin 50 50 Vin Better power transfer 2 1 10 6 Vin 6 1 10 50 Vin Better efficiency The IOBoard function generator has an output impedance of much less than 50Ω, so we can ignore it. Our battery however is a different story, as you will see in the experiment. Kirchoff’s Laws sum of voltages in any loop is zero sum of currents entering a junction is the same as the sum of the currents leaving a junction Circuit Analysis (Combination Method) Useful Aside: SI Suffixes pico nano micro milli Kilo Mega Giga Tera p n m (u) m k M (Meg) G T 10-12 10-9 10-6 10-3 103 106 109 1012 1 1 n G G n 1 1 m M M m 1 1 m k k m ex. 1 1 1 0.1m 10k 10 k Part C Capture • Create circuits visually • Set up simulation parameters PSpice • Analyzes circuit • Displays results Capture Simulations run to time # cycles freq step size run to time 1000 PSpice Note: To get copy of trace into word use Window menu ”copy to clipboard” Cursors Note: You can drag the left mouse button to move one cursor and the right mouse button to move the other. Adding Traces Note: To add a trace use Trace menu ”Add Trace” Part D Oscilloscopes Lissajous Figures Cathode Ray Tubes y input x input Variation in potential difference (voltage) placed on plates causes electron beam to bend different amounts. “Sweep” refers to refreshing repeatedly at a fixed rate. http://www.chem.uiuc.edu/clcwebsite/video/Cath.avi Cathode Ray Tube Animation http://webclass.cqu.edu.au/Units/81120_FOCT_Har dware/Study_Material/Study_Guide/chap2/toc.html Oscilloscopes Horizontal sweeps at a constant rate. Vertical plates are attached to an external voltage, the signal you attach to the scope. http://boson.physics.sc.edu/~hoskins/Demos/Cath odeRay.html Lissajous Figures http://encyclozine.com/Science/Mathematics/Graphs/Lissajous/ Lissajous Figures Normally the scope will plot a voltage signal with respect to time. In a Lissajous figure, two voltage signals are plotted against each other. Lissajous Example 1 t1 Lissajous Example 2 Lissajous Example 3 More Figures In Class Problem Across the top please put: Name: Section ((MR) or (TF)): Date P1 Question 1: From diagram A: Which of the following statements is true given the direction of the current flow. c.) P2 > P1 I Pump Current flow from high pressure to low pressure therefore P2 must be greater than P1. Question 2: Draw the circuit equivalent of diagram A, label current flow and voltage (+ and – on the voltage source). Question 3: Draw an AC signal with the following parameters Vp-p=6V Vave=0V Frequency=2KHz Label the axis, label the amplitude and period I Constriction P2 Diagram A Vsour ce R1